The disclosure relates to semiconductor devices, and more particularly, to a refresh method of adaptively changing an all-bank-refresh (ABR) cycle of self-refreshing a memory device according to temperature.
Volatile memory devices such as a dynamic random access memory (DRAM) perform a refresh operation to retain data stored therein. The DRAM performs auto-refresh to refresh memory cell rows according to a refresh command periodically supplied thereto, and perform self-refresh to refresh the memory cell rows in response to a built-in timer according to an ‘enter self-refresh’ command SRE and an ‘exit self-refresh’ command SRX. If an all-bank-refresh (ABR) operation is performed whenever self-refresh is performed and the ‘enter self-refresh’ command SRE is frequently given, refresh operations are often performed more frequently than is necessary to retain data of DRAM cells. Accordingly, refresh time of the DRAM may unnecessarily increase, refresh power consumption may increase and thus the performance of the DRAM may be degraded.